JP2010274491A - Tire vulcanizing method and bladder used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire vulcanizing method that improves transmissibility of heat of a heating medium to tires without impairing durability of a bladder, and to provide a bladder to be used for the method. <P>SOLUTION: Tires are vulcanized by using a bladder 1 in which at least a portion 21 of the inner face 14 is composed of a face with a number of blind holes arranged on a smooth plane surface. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tire vulcanizing method for vulcanizing a tire by supplying heat through at least a bladder pressed against the inner surface of the tire, and in particular, for uniformly vulcanizing a tire. It relates to what can be done.

  FIG. 1 is a cross-sectional view schematically showing a tire accommodated in a vulcanization mold and being vulcanized. A tire vulcanizer is provided with a bladder 90 and a vulcanization mold 2 and a tire 10. When vulcanizing the tire, the vulcanizing mold 2 that molds the outer surface 12 of the tire is heated to transmit heat from the vulcanizing mold 2 to the inside of the tire through the outer surface 11 of the tire and push it to the inner surface 11 of the tire. The heat of the heat medium 3 accommodated in the applied bladder 90 is transmitted from the tire inner surface 11 to the inside of the tire through the bladder 90 to vulcanize rubber constituting the tire. As the heat medium 3, steam, pressurized hot water, high-temperature and high-pressure gas, or the like is usually used.

  In this manner, the bladder 90 functions as a variable shape container that can enclose the heat medium 3 accommodated therein. And, when the bladder 90 is pressed against the inner surface of the unvulcanized tire 10, after placing the unvulcanized tire 10 on the outside of the bladder that has been made into a cylindrical state in advance, a pressurized fluid is caused to flow into the bladder, Further, when the vulcanized tire is removed from the bladder 90, the bladder 90 is formed into a cylindrical shape by making the inside of the bladder 90 a negative pressure.

  The bladder 90 having such a function is capable of efficiently transferring the heat of the heat medium to the tire, and since deformation is unavoidable every time one tire is vulcanized, it has high durability against expansion and contraction. In particular, in order to ensure durability, uniform expansion and contraction is an essential characteristic.

  In order to provide the functions as described above, the bladder 90 is usually made of rubber having a constant thickness, and the outer surface and inner surface thereof are both smooth surfaces (see, for example, Patent Document 1).

JP 2008-207541 A

  However, in order to efficiently transfer the heat of the heat medium to the tire, it is preferable that there is no bladder if possible. From this point of view, there is a bladder that can improve heat transfer rate while ensuring durability. It has been demanded.

  The conventional vulcanization method also has the following problems. That is, conventionally, since the bladder has a uniform surface with a uniform thickness as described above, the heat transferred to the shoulder portion of the tire is schematically shown by an arrow in the cross-sectional view of FIG. The tire 10 has heat Q2 from the vulcanization mold 1 and heat Q1 transmitted from the heat medium 3 through the bladder 90, and is transmitted to the tire 10 through the tire inner surface 11 through the bladder 90. Regardless of the part of the tire, the heat Q1 is uniform in the amount of heat per unit time per unit area, whereas the tire has a different thickness for each part, for example, thick in the shoulder part of the tire, The sidewall portion is thin, and the temperature rise rate inside the tire is different for each part, and is slow at the shoulder portion and fast at the sidewall portion.

  Therefore, the degree of vulcanization of the tire (that is, the ratio of the vulcanized portion of the rubber) varies depending on the part. If the degree of vulcanization of the rubber is low and the unvulcanized state cannot be obtained, the expected physical properties cannot be obtained, and if the degree of vulcanization is too high, the rubber tends to deteriorate. However, the conventional vulcanization method has a problem that the degree of vulcanization varies depending on the site as described above. This problem has been addressed by, for example, selecting a rubber material that can obtain the necessary physical properties over a wide range of vulcanization degrees. There is also a problem that the selection range becomes narrow, and improvement has been demanded.

  The present invention has been made in view of such problems, and a first object is to improve the transmission rate when transferring the heat of the heat medium to the tire without impairing the durability of the bladder. The second object of the present invention is to provide a tire vulcanizing method and a bladder used in the method, and a second purpose is to provide a necessary and sufficient degree of vulcanization over all parts even if the tire thickness is nonuniform in each part. It is to provide a tire vulcanizing method capable of imparting to a rubber and a bladder used in the method.

<1> is a vulcanizing method for a tire in which the tire is vulcanized by supplying heat through a bladder pressed against the inner surface of the tire,
This is a tire vulcanizing method in which at least a part of the inner surface vulcanizes a tire using a bladder having a bottomed hole-attached surface in which a large number of bottomed hole portions are arranged in a plane on a smooth surface.

  <2> In <1>, the surface with a bottomed hole is limited to a portion including a portion corresponding to the thickest tire portion, and the remaining portion of the inner surface of the bladder is a smooth surface. This is a tire vulcanizing method characterized by comprising:

  <3> is a tire vulcanizing method according to <2>, wherein the bottomed hole portions all have the same cross-sectional shape and are arranged in two different directions from each other at a constant arrangement pitch.

  <4> is a method for vulcanizing a tire according to <2> or <3>, wherein the opening of the bottomed hole has a shape of a circle, an ellipse, or an ellipse. .

  <5> is characterized in that, in <2> or <3>, the cross-section in the depth direction of the bottomed hole portion is in the shape of a semicircle, a semi-ellipse, or a semi-ellipse. 2. The tire vulcanizing method according to 2 or 3.

  <6> is any one of <2> to <5>, wherein the bottomed hole portion has a maximum depth of 0.3 to 0.7 times a bladder thickness corresponding to the deepest bottom portion. This is a tire vulcanization method.

  <7> is the tire vulcanization according to any one of <2> to <6>, wherein the diameter of the largest circle inscribed in the opening of the bottomed hole is 1.8 to 8.0 mm Is the method.

  <8> is the tire vulcanizing method according to any one of <2> to <7>, wherein the arrangement pitch is 3 to 10 mm.

  <9> is any one of <2> to <8>, wherein the maximum thickness of the bladder portion having the bottomed hole-attached surface is 1.05 to 1.3 times the thickness of the remaining bladder portion. This is a characteristic method of vulcanizing a tire.

  <10> In any one of <1> to <9>, the tire portion corresponding to the bladder portion having the bottomed hole-attached surface includes a portion from a shoulder portion of the tire to a tread portion and a bead portion. A tire vulcanizing method characterized by being included.

  <11> is a bladder used in the tire vulcanizing method according to any one of <1> to <10>.

  According to <1>, when a tire is vulcanized, because at least a part of the inner surface uses a bladder having a bottomed hole-attached surface in which a large number of bottomed hole portions are arranged on a smooth surface. The surface area of the inner surface of the bladder where the bladder and the heat medium come into contact with each other can be greatly increased, and the transmission rate when the heat of the heat medium is transferred to the tire can be improved, and the surface area of the inner surface of the bladder can be increased. Compared to the case where a large number of ridges are arranged, for example, instead of the bottomed hole portion, the elongation of the bladder can be made independent of the direction.

  According to <2>, the surface with the bottomed hole portion is provided only in a portion including a portion corresponding to the thickest tire portion, and a remaining portion of the inner surface of the bladder is configured by a smooth surface. Therefore, on the inner surface of the tire part with a large wall thickness, the bladder part whose contact area with the heat medium is widened by having a surface with a bottomed hole part is pressed, and heat is only applied to this part. The transmission speed is increased, and as a result, a necessary and sufficient degree of vulcanization can be imparted to the rubber regardless of the part.

  <3> According to <3>, since the bottomed holes all have the same cross-sectional shape and are arranged in two different directions from each other at a constant arrangement pitch, the dependency of the tire elongation on the direction of force is reduced. It can be made smaller.

  According to <4>, since the opening of the bottomed hole has a shape of a circle, an ellipse, or an ellipse, stress is concentrated due to the corner of the opening, and durability is reduced. Can be suppressed.

  <5> According to the depth direction cross-section of the bottomed hole portion, because it is a semicircle, semi-oval, or semi-elliptical shape, in the depth direction cross-section of the bottomed hole portion, For example, it is possible to suppress the stress from being concentrated and the durability from being lowered due to the corners at the bottom.

  <6> is such that the maximum depth of the bottomed hole portion is 0.3 to 0.7 times the thickness of the bladder corresponding to the deepest bottom portion. The hole becomes too shallow, making it difficult to achieve the effect of increasing the heat transfer area. On the other hand, if this value exceeds 0.7, the depth of the bottomed hole will be less than the bladder thickness. It becomes too deep, and the unevenness due to the bottomed hole on the inner surface of the bladder also affects the outer surface of the bladder, which is transferred to the inner surface of the tire.

  <7> is the diameter of the smallest circle among the circles circumscribing the opening of the bottomed hole, and is 1.8 to 8.0 mm. When this value is less than 1.8 mm, The flow of the medium is suppressed and the heat transfer speed is not effectively increased.In particular, when the heat medium is steam, the drain is accumulated in the bottomed hole portion, and the heat transfer is suppressed. In the case of a person exceeding 8.0 mm, the unevenness due to the bottomed hole on the inner surface of the bladder also affects the outer surface of the bladder, which is transferred to the inner surface of the tire.

  <8> is that the arrangement pitch is 3 to 10 mm. If this value is less than 3 mm, the pitch becomes too fine and the bottomed hole is the starting point of the rubber of the bladder. On the other hand, if this value exceeds 10 mm, temperature unevenness is likely to occur on the tire inner surface side of the bladder, and this temperature unevenness may cause uneven vulcanization distribution of the tire. End up.

  <9> means that the maximum thickness of the bladder part having the bottomed hole-attached surface is 1.05 to 1.3 times the thickness of the remaining bladder part, and when this value is less than 1.05 times If this value exceeds 1.3 times, the deformation of the bladder will not be uniform and the bladder will be damaged when it is taken in and out of the tire. It becomes easy.

  <10> According to the tire portion corresponding to the bladder portion having the bottomed hole-attached surface, the portion from the shoulder portion of the tire to the tread portion and the bead portion are included. When the vulcanization time is set so that the degree of vulcanization at the portions is completely satisfied, over-vulcanization at other portions can be prevented.

  According to <11>, since the bladder of this invention is used for the vulcanizing method for tires described above, the effects as described for these vulcanizing methods can be achieved.

It is sectional drawing which shows the tire vulcanized using the conventional bladder. It is a schematic diagram which shows transmission of the heat | fever to a tire in the conventional vulcanizing method of a tire. It is sectional drawing which shows the tire vulcanized using the bladder concerning this invention. It is a mimetic diagram showing transfer of heat to a tire in a vulcanizing method of a tire concerning the present invention. It is a top view which illustrates the bottomed hole part attaching surface of a bladder. It is sectional drawing which illustrates the bladder part which has a surface with a bottomed hole part. It is sectional drawing which illustrates the modification of the bladder part which has a surface with a bottomed hole part.

Embodiments of the present invention will be described with reference to the drawings. FIG. 3 is a cross-sectional view schematically showing a state during vulcanization of a tire vulcanized using the bladder of the embodiment of the present invention. The bladder 1 of this embodiment is a conventional one shown in FIG. Used in a mode of replacing the bladder 90. The conventional bladder 90 is made of a thin rubber having a constant thickness, and the outer surface and the inner surface are both uniform smooth surfaces. Among them, at least a portion 21 has a feature that it is formed of a surface with a bottomed hole portion in which a large number of bottomed hole portions are arranged in a planar shape on a smooth surface.
Here, the bladder inner surface 14 in this specification refers to the inner surface of the bladder 1, that is, the surface in contact with the heat medium.

When a tire is vulcanized using such a bladder 1, the surface area of the bladder inner surface that is actually in contact with the heat medium is equal to the amount of the bottomed hole portion. The heat transfer rate of the heat medium to the tire can be improved, and the vulcanization time can be shortened.
Here, for the first purpose of the present invention described above, that is, to improve the transmission rate when the heat of the heat medium is transmitted to the tire, the entire inner surface of the bladder is formed with the bottomed hole-attached surface 21. In order to realize the second object of the present invention, that is, to provide the rubber with a necessary and sufficient degree of vulcanization over all parts, the bottomed hole-attached surface 21 is preferably formed. It is preferable to provide only a part including a part corresponding to the thickest tire part, and to make the remaining part of the bladder inner surface 14 a smooth surface. This will be described in detail below.

  FIG. 4 is a schematic diagram showing the heat transmitted to the shoulder portion of the tire when the tire is vulcanized using such a bladder 1, and is constituted by a smooth surface of the bladder inner surface 14. In the portion 22, since there is no bottomed hole portion, the area where the bottomed hole portion is ignored, that is, the apparent area and the heat transfer area that actually contacts the heat medium are the same, whereas the bottomed hole portion In the abutting surface 21, since the actual heat transfer area is larger due to the bottomed hole portion than the apparent area, the unit area transmitted to the tire through the bladder surface portion 22 made of a smooth surface. The amount of heat per unit time and the amount of heat per unit time transmitted to the tire through the bottomed hole-attached surface 21 is larger than the amount of heat per unit time. Shoulder part with low heat transfer coefficient For example, a tire portion (for example, a sidewall portion) that is thin and has a high heat transfer rate to the inside has almost the same temperature increase rate inside, and therefore gives a uniform degree of vulcanization throughout the tire. Can do.

  FIG. 5 is a plan view of the bottomed hole-attached surface 21 of the bladder 1, and FIG. 6 is a cross-sectional view thereof. As shown in the figure, the bottomed hole-attached surface 21 is configured by arranging a large number of bottomed hole portions 32 in a planar shape on a smooth surface 31. By this, for example, a plurality of ridges are formed on the inner surface of the bladder. In contrast to the arrangement of the, the direction dependency of the stress acting on the bladder 1 can be suppressed. The bottomed hole portions 32 all have the same cross-sectional shape and are arranged in two different directions (for example, a direction corresponding to the tire width direction and a direction corresponding to the tire circumferential direction) at a constant arrangement pitch p. It is preferable that the direction dependency of the stress acting on the bladder 1 can be more effectively suppressed.

  Further, the opening 33 of the bottomed hole 32 has a shape of a circle, an ellipse, or an ellipse, and further, the cross-section in the depth direction of the bottomed hole 32 has a semicircle, a semi-ellipse, or A semi-elliptical shape is preferable, and the absence of corners in these portions prevents stress concentration and improves durability.

  When the bottomed holes 32 are arranged in two directions at a constant pitch p, in order to obtain a sufficient surface area for heat transfer and make the durability against elongation equal to the part without the bottomed holes 32, The maximum depth d of the bottomed hole portion 32 is set to 0.3 to 0.7 times the bladder thickness a corresponding to the deepest bottom portion, and the smallest circle among the circles circumscribing the opening 33 of the bottomed hole portion 32 is selected. The diameter D is set to 1.8 to 8.0 mm, the arrangement pitch p is set to 3 to 10 mm, and the maximum thickness b of the bladder portion having the bottomed hole-attached surface 21 is set to an inner surface 22 formed of a smooth surface. It is preferable that the thickness t be 1.05 to 1.3 times the thickness t of the bladder portion.

但し、p : 配列ピッチ
r : 有底穴部開口部の半径
d : 有底穴部の深さ
a : 最も深い底部分に対応するブラダー厚さ
b : 有底穴部付面を有するブラダー部分の最大厚さ
t : 平滑面で構成された内面を有するブラダー部分の厚さ When the bottomed hole portion 32 has a shape in which a cylinder is hollowed out, the increase rate S of the heat transfer area with respect to the apparent area of the actual heat transfer area on the bottomed hole-attached surface 21 is expressed by the formula (1 In order to make the elongation of the bladder portion having the bottomed hole-attached surface 21 equal to the elongation of the bladder portion having the inner surface 22 made only of the smooth surface, the equation (2) Therefore, when determining the dimensional parameters of the bottomed hole-attached surface, the condition of the equation (2) and the heat transfer area increase rate S obtained by the equation (1) are set to a predetermined value. What is necessary is just to select under the conditions set as the value set so that the vulcanization degree may become uniform when vulcanization time is reached.

Where p: arrangement pitch
r: Radius of the bottomed hole opening
d: depth of bottomed hole
a: Bladder thickness corresponding to the deepest bottom
b: Maximum thickness of bladder part with bottomed hole
t: Thickness of bladder part with inner surface composed of smooth surface

  FIG. 7 is a cross-sectional view of a portion having a bottomed hole-attached surface 21 of a bladder according to a modification of the embodiment. This example is different from the embodiment in the case of the example shown in FIG. Whereas the cross section of the bottomed hole 32 has a square shape, the bottomed hole 32A shown in FIG. 6 has a semi-circular cross section, and only this point has been described above. It is different from the embodiment.

DESCRIPTION OF SYMBOLS 1 Bladder 2 Vulcanization mold 3 Heat medium 10 Tire 11 Tire inner surface 12 Tire outer surface 13 Thickest portion of tire 14 Inner surface of bladder 21 Portion of inner surface of bladder with bottomed hole portion 22 Bladder Part of inner surface constituted by smooth surface 31 Smooth surface 32 Bottomed hole part 33 Opening part of bottomed hole part

Claims (11)

At least in a tire vulcanizing method for vulcanizing a tire by supplying heat through a bladder pressed against the inner surface of the tire,
A tire vulcanizing method in which at least a part of an inner surface vulcanizes a tire using a bladder having a surface with a bottomed hole portion in which a number of bottomed hole portions are arranged in a plane on a smooth surface.   The bottomed surface with a hole is limited to a portion including a portion corresponding to the thickest tire portion, and the remaining portion of the inner surface of the bladder is a smooth surface. The tire vulcanizing method according to claim 1.   3. The tire vulcanizing method according to claim 2, wherein the bottomed hole portions all have the same cross-sectional shape and are arranged in two different directions from each other at a constant arrangement pitch.   4. The tire vulcanizing method according to claim 2, wherein the opening of the bottomed hole has a shape of a circle, an ellipse, or an ellipse. 5.   4. The tire vulcanizing method according to claim 2, wherein a cross section in the depth direction of the bottomed hole portion has a shape of a semicircle, a semi-ellipse, or a semi-ellipse.   The tire vulcanization method according to any one of claims 2 to 5, wherein a maximum depth of the bottomed hole portion is 0.3 to 0.7 times a bladder thickness corresponding to the deepest bottom portion.   The tire vulcanizing method according to any one of claims 2 to 6, wherein the diameter of the largest circle inscribed in the opening of the bottomed hole is 1.8 to 8.0 mm.   The tire vulcanizing method according to any one of claims 2 to 7, wherein the arrangement pitch is 3 to 10 mm.   The tire thickness according to any one of claims 2 to 8, wherein the maximum thickness of the bladder portion having the bottomed hole-attached surface is 1.05 to 1.3 times the thickness of the remaining bladder portion. Sulfur method.   The tire portion corresponding to the bladder portion having the bottomed hole-attached surface includes a portion from a shoulder portion of the tire to a tread portion and a bead portion. The method for vulcanizing a tire according to 1.   A bladder used in the method for vulcanizing a tire according to any one of claims 1 to 10.

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